Technical Field
Embodiments of the present disclosure relate to a surface-emitting laser, a surface-emitting laser array, a laser device, an ignitor, an internal combustion engine, an optical scanner, an image forming apparatus, a light transmission module, and a light transmission system. More specifically, the embodiments of the present disclosure relate to a vertical-cavity surface-emitting laser, a surface-emitting laser array including a plurality of surface-emitting lasers, a laser device including the surface-emitting laser array, an ignitor including the laser device, an internal combustion engine including the ignitor, an optical scanner including the surface-emitting laser or the surface-emitting laser array, an image forming apparatus including the optical scanner, an image forming apparatus including the optical scanner, a light transmission module including the surface-emitting laser array, and a light transmission system including the light transmission module.
Related Art
A vertical-cavity surface-emitting laser (VCSEL) is a laser that emits light in a direction perpendicular to a substrate of the surface-emitting laser. Such a surface-emitting laser that is suitable for two-dimensional array achieves lower cost and less power consumption than a surface-emitting semiconductor laser that emits light in a direction parallel with a substrate. This is why the VCSEL has been drawing attentions.
The surface-emitting laser includes a current constriction layer that is formed by selectively oxidizing a selectively-oxidized layer to increase current injection efficiency.
Examples of application of such a surface-emitting laser in applied fields include a writing light source with, e.g., an oscillation wavelength of 780 nm for a writing system in printers and a writing light source with, e.g., oscillation wavelengths of 780 nm and 850 nm for reading and writing in optical disc devices. The surface-emitting lasers are expected to be applied to pump sources of solid-state lasers. In such a case, there is a demand for the surface-emitting lasers to have a lower threshold value and higher output power to be successfully applied to such devices.